1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
|
/* -------------------------------------------------------------- */
/* (C)Copyright 2006,2007, */
/* International Business Machines Corporation, */
/* Sony Computer Entertainment, Incorporated, */
/* Toshiba Corporation, */
/* */
/* All Rights Reserved. */
/* */
/* Redistribution and use in source and binary forms, with or */
/* without modification, are permitted provided that the */
/* following conditions are met: */
/* */
/* - Redistributions of source code must retain the above copyright*/
/* notice, this list of conditions and the following disclaimer. */
/* */
/* - Redistributions in binary form must reproduce the above */
/* copyright notice, this list of conditions and the following */
/* disclaimer in the documentation and/or other materials */
/* provided with the distribution. */
/* */
/* - Neither the name of IBM Corporation nor the names of its */
/* contributors may be used to endorse or promote products */
/* derived from this software without specific prior written */
/* permission. */
/* Redistributions of source code must retain the above copyright */
/* notice, this list of conditions and the following disclaimer. */
/* */
/* Redistributions in binary form must reproduce the above */
/* copyright notice, this list of conditions and the following */
/* disclaimer in the documentation and/or other materials */
/* provided with the distribution. */
/* */
/* Neither the name of IBM Corporation nor the names of its */
/* contributors may be used to endorse or promote products */
/* derived from this software without specific prior written */
/* permission. */
/* */
/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND */
/* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, */
/* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF */
/* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE */
/* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR */
/* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, */
/* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT */
/* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; */
/* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) */
/* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN */
/* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR */
/* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, */
/* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
/* -------------------------------------------------------------- */
/* PROLOG END TAG zYx */
#ifdef __SPU__
#ifndef _RECIPD2_H_
#define _RECIPD2_H_ 1
#include <spu_intrinsics.h>
/*
* FUNCTION
* vector double _recipd2(vector double value)
*
* DESCRIPTION
* The _recipd2 function inverts "value" and returns the result.
* Computation is performed using the single precision reciprocal
* estimate and interpolate instructions to produce a 12 accurate
* estimate.
*
* One (1) iteration of a Newton-Raphson is performed to improve
* accuracy to single precision floating point. Two additional double
* precision iterations are needed to achieve a full double
* preicision result.
*
* The Newton-Raphson iteration is of the form:
* X[i+1] = X[i] * (2.0 - b*X[i])
* where b is the input value to be inverted
*
*/
static __inline vector double _recipd2(vector double value_d)
{
vector unsigned long long zero = (vector unsigned long long) { 0x0000000000000000ULL, 0x0000000000000000ULL };
vector unsigned long long expmask = (vector unsigned long long) { 0x7FF0000000000000ULL, 0x7FF0000000000000ULL };
vector unsigned long long signmask = (vector unsigned long long) { 0x8000000000000000ULL, 0x8000000000000000ULL };
vector float x0;
vector float value;
vector float two = spu_splats(2.0f);
vector double two_d = spu_splats(2.0);
vector double x1, x2, x3;
vector double bias;
/* Bias the divisor to correct for double precision floating
* point exponents that are out of single precision range.
*/
bias = spu_xor(spu_and(value_d, (vector double)expmask), (vector double)expmask);
value = spu_roundtf(spu_mul(value_d, bias));
x0 = spu_re(value);
x1 = spu_extend(spu_mul(x0, spu_nmsub(value, x0, two)));
x1 = spu_mul(x1, bias);
x2 = spu_mul(x1, spu_nmsub(value_d, x1, two_d));
x3 = spu_mul(x2, spu_nmsub(value_d, x2, two_d));
/* Handle input = +/- infinity or +/-0. */
vec_double2 xabs = spu_andc(value_d, (vec_double2)signmask);
vec_ullong2 zeroinf = spu_or(spu_cmpeq(xabs, (vec_double2)expmask),
spu_cmpeq(xabs, (vec_double2)zero));
x3 = spu_sel(x3, spu_xor(value_d, (vector double)expmask), zeroinf);
return (x3);
}
#endif /* _RECIPD2_H_ */
#endif /* __SPU__ */
|
